1. Field of the Invention
The present invention relates to a method and apparatus for configuring signaling radio bearer in a wireless communications system, and more particularly, to a method and apparatus for accurately configuring signaling radio bearer in a wireless communications system, so as to enhance information security.
2. Description of the Prior Art
The third generation (3G) mobile telecommunications system provides high frequency spectrum utilization, universal coverage, and high quality, high-speed multimedia data transmission, and also meets all kinds of QoS requirements simultaneously, providing diverse, flexible, two-way transmission services and better communication quality to reduce transmission interruption rates. According to the related protocol specifications, a protocol stack of the 3G mobile telecommunications system can be segmented into access stratum (AS) and non-access stratum (NAS). The AS comprises a Radio Resource Control (RRC), Radio Link Control (RLC), Media Access Control (MAC), Packet Data Convergence Protocol (PDCP), Broadcast/Multicast Control (BMC) and other sub-layers of different functions. Those skilled in the art are familiar with the operation of the above-mentioned sub-layers; therefore, they will not be further mentioned.
Long Term Evolution wireless communications system (LTE system), an advanced high-speed wireless communications system established upon the 3G mobile telecommunications system, supports only packet-switched transmission, and tends to implement both Medium Access Control (MAC) layer and Radio Link Control (RLC) layer in one single communication site, such as in Node B alone rather than in Node B and RNC (Radio Network Controller) respectively, so that the system structure becomes simpler.
A complete protocol specification is accomplished with lasting discussion, editing, and modification. Now, parts of the LTE structure are under Technical Report (TR) stage, meaning that the related protocol specifications are not finished. Therefore, many functions are still For Further Study (FFS).
According to the current system structure of the LTE system, the following can be summarized:
1. For User Plane, the layer structure is, from low to high, PHY (Physical layer), MAC, RLC, and PDCP.
2. For Control Plane, the layer structure is, from low to high, PHY, MAC, RLC, RRC, PDCP, and NAS.
3. For User Plane, ciphering is performed in PDCP.
4. For Control Plane, ciphering and IP for RRC messages are done in RRC and ciphering and IP for NAS messages are done in PDCP.
5. NAS messages may or may not be concatenated with RRC messages.
6. No IP from RRC for non-concatenated messages.
7. IP from RRC for concatenated NAS messages is FFS.
8. Protocol error detection and recovery function is performed in RLC.
Therefore, the prior art does not well specify configuration of signaling radio bearer, and the operation of ciphering from RRC for non-concatenated NAS messages.